Mean effective pressure indicator for internal-combustion engines



March 17, 1925. v 1,530,457

W. ARSCHAULOFF MEAN EFFECTIVE PRESSURE INDICATOR FOR INTERNAL COMBUSTION ENGINES Filed Nov. 29, 1921 II-IIII ifli/zwias: I Jrmeiziar- Patented Mar. 17, 1925.

UNITED STATES 1,530,457- PATENT OFFICE.

v wamivi' i izsonautorr, or PARIS, FRANCE. j I

MEAN EFFECTIVE ranssunn INDICATOR For. m'rERNAL-co vreUsTioN Enemies.

Application filed November 29, 1921. Serial No. 518,685.

To all whom it may concern: Be it known that I, VVADIM ARsoI-IAULorF, a Russian subject, and aresident of Paris, in the 'Republic of France, have invented certain new and useful Improvements in Mean Effective Pressure- Indicators for Internal-Combustion Engines, of which the following is a specification.

This invention relates to an apparatus for indicating the mean effective pressure in internal-combustion engines and has for its object to facilitate the supervision of multicylinder engines by enabling the supervisor v to readily perceive at any time the mean effective pressure in each cylinder, thus avoiding the necessity of taking numerous indicator diagramsin order to ensure that the power developed is equally distributed througlioutthe several cylinders.

1 The improved indicatoris applicable to.

any type of internal combustion engine having a fixed cycle and is particularly applicable to Diesel engines which have atypical indicator diagram. r

The indicatorcomprisesa closed vessel orv chamber in constant communication through a small orifice or narrow bore tube with the compression and combustion chamber of the cylinder. When the engine is working, therefore, a certain pressure will gradually arise in the vessel and thevariation of this 7 pressure can be reduced by increasing the capacity of the vessel or. by reducing the bore of the orifice or connecting tube, The pressure in the vessel will be dependent on the mean effective pressure in the cylinder.

In order that the invention may be more clearly understood reference is hereinafter made to the accompanying drawings whereon V Figs. 1 and 2 are diagrams illustrating the compression and expansion when the cylinder is working almost without combustion. Figs. 3 and {t are corresponding diagrams when the cylinder is working at full load.

Fig. 5 is a vertical section and Fig. 6 av the cylinder is working almost withoutcombustion, when the mean effecti-vepressure is zero and the expansion line coincides with the compression line and (2) when the'cylinder is working-at full load and a meaneffective pressure of 7 atmospheres.

The first case is illustrated by the grams in Figs. 1.j and 2. Fig. 1 shows the compression vline o, b, 0 and the expansion line 0,. b, obtained with a mean effective pressure P equal to zero.

' dia- In the diagram shown in Fig. 2, the same compression and expansion lines. are plotted as time abscissa and pressure OI'CllDZLlK-BS,

It can be assumed with a fairdegi'ee of accuracythat in passing through a very nar row-bore tube the weight of gas periodicah ly passing through the tube in both directions between the cylinder and vessel corresponds to the time and pressure differences in the cylinder and inthe vessel. Consequently, a mean pressure gradually arises in the vessel. If the area a, b, c, b, w of F ig. 2 is distributed over its length, a value of approximately 5.2 atmospheres is obtained. That is to say, whilst the mean effective pressure P in one cylinder of the two-stroke Diesel engine is zero, the pressure in the vessel is approximately 5.2 atmospheres.

The second case is illustrated by'the diagrams in Figs. 3 and 4 where the cylinder generates its full power with a mean ,eft'ective pressure P:7 atmospheres.

3 Proceeding as in the first case. one obtains a pressure of about 8.1 atmospheres in the vessel fora mean cylinder pressure of 7 atmospheres. In this manner a complete pres sure diagram is obtained.

These theoretical calculations have been verified by numerous actual tests with substantially identical resultant figures.

From the foregoing, it is apparent that the diaphragm or Bourdon tube of the gauge on the vessel must have an initial tension such that the pointer only leaves the zero mark of the scale at a pressure inthe vessel of 5.2 atmospheres,"corresponding to the zero cylinder pressure. The scale should be so graduated that, for pressures between 5.2 and 8.1 atmospheres in the vessel, the pointer traverses from zero to 7 onthe scale. The pointer must register with the mark 7 when the pressure in the vessel is 8.1 atmospheres. The gauge therefore indicates the mean effective pressure in the cylinder and not the pressure in the vessel. Where the pointer is actuated by the tube of a Bourdon gauge, for instance, the tube may be given an initial tension by means of a relatively stationary set screw bearing radially against the free end of the tube and on the inner side thereof. v

The scale must be similarly graduated for other types of internal combustion engines. The graduations are preferably verified by taking diagrams from the engine.

Figs. 5 and 6 illustrate the construction of the indicator. The vessel 1 is in constant communication with the combustion chamber-of the cylinder through a verv narrowbore tube 3. The tube may be replaced by any other means adapted to considerably restrict the gas passage. The gauge 2' is fitted with a scale graduated as above described and indicates not the pressure in the .vessel 1 but the corresponding mean ef- Claims: 1. A meanefilectrve pressure indicator for to register the-meanetlective pressure in the engine cylinder and not the pressure in the vessel.

2. A mean effective pressure indicator for internal combustion engines comprising 1 chamber having restricted and continuous communication with the combustion chain-- ber of the engine cylinder, a pressure gauge in communication with said chamber. an index pointer, a scale over which said index pointer is adaptedto travel and means for actuating said index pointer by the variations of pressure in said chamber, said means being initially under tension so that the'pointer only leaves the zero mark of the scale at a pressure corresponding to zero cylinder pressure.

In'testimony whereof I hereunto aiiix my signature.

"W'ADIM LX'RSCHAULOFF.

internal combustion engines comprising a 

